JP2016051899A - Coil component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil component having a composite magnetic material improving the wettability of alloy particle surface and resin, excellent in liquidity, and capable of increasing the filling rate of alloy particles even if a high pressure is not applied while molding.SOLUTION: A coil component is composed of a composite magnetic material containing metal magnetic particles where the oxygen ratio of the surface of alloy particles is 50% or less, and resin, and a coil. Preferably, the oxygen ratio is 30-40%.SELECTED DRAWING: None

Description

  The present invention relates to a composite magnetic material including metal magnetic particles and a resin, a magnetic body in which the composite magnetic material has a predetermined solid shape, and a coil component including the magnetic body as constituent elements.

  Since electronic devices such as portable devices have been improved in performance, high performance is also required for the components used. Furthermore, since the number of components mounted on electronic equipment is increasing, the trend of downsizing of components is further increased. In particular, high performance is demanded even for small parts such as 3 mm or less, which have been frequently used so far, and studies using metal magnetic materials are underway.

  As a coil component using a metal magnetic material, as described in Patent Document 1, there is a method of embedding a coil in a green compact of an alloy powder. In the technique of Patent Document 1, studies are made to reduce the loss by using an alloy powder having a relatively small particle size. However, if the particle size is simply reduced, the specific surface area increases, and the moldability tends to decrease. Therefore, as a result, a green compact was formed by applying a high molding pressure.

JP 2013-145866 A

  However, in the conventional method, as shown in the example of Patent Document 1, a very high forming pressure of, for example, 600 MPa is required, and the stress applied to the coil cannot be ignored at such a pressure. In particular, a coil using a thin conductive wire is easily deformed or easily broken. As described above, since a high molding pressure is premised, the choices of usable conductors are limited. In addition, stress is applied to the alloy particles by applying a high pressure, and the magnetic permeability may be lowered. Another method includes surface treatment of metal magnetic particles. For example, by using a coupling agent, the metal magnetic particles have improved wettability, and a stable composite magnetic material can be obtained. However, this method also causes a decrease in the filling rate of alloy particles due to the presence of the coupling agent.

  For this reason, forming a magnetic material without relying on high pressure is important for further miniaturization. An object of the present invention is to provide a composite magnetic material that does not require a high pressure during molding, and to provide a coil component having such a composite magnetic material.

  As a method for forming a magnetic body that does not require high pressure, there is a warm molding in which a composite magnetic material of metal magnetic particles and a resin is used and this resin is dissolved. In warm molding, it is necessary to increase the proportion of the resin, and it is difficult to increase the filling rate of the metal magnetic particles as in compacting. For this reason, this inventor examined on the assumption that the ratio of additives other than a metal magnetic particle is not increased. As a result, it has been found that the oxidation state on the surface of the metal magnetic particles affects the fluidity of the composite magnetic material of magnetic particles and resin, and improves the filling property. Specifically, the amount of oxygen on the surface of the metal magnetic particles is small, the compatibility with the resin is improved, and the viscosity properties as a composite magnetic material mixed with the metal magnetic particles are lowered. That is, it has been found that by reducing the viscosity property of the composite magnetic material of magnetic particles and resin, the fluidity is improved and high filling is possible.

As a result of further diligent examination based on the above findings, the present inventor completed the present invention as follows.
(1) A coil component comprising a composite magnetic material containing alloy particles and a resin and a coil, wherein the oxygen ratio of the surface of the alloy particles is 50% or less.
(2) The coil component according to (1), wherein the oxygen ratio is 30 to 40%.
(3) A coil component according to any one of (1) and (2), comprising a coil embedded in a composite magnetic material.
(4) The coil component according to any one of (1) and (2), wherein the coil component has a coil formed inside the composite magnetic material.

  According to the present invention, the use of alloy particles having an oxygen ratio of 50% or less on the surface of the alloy particles improves the wettability between the surface of the alloy particles and the resin. The viscosity resistance of this composite magnetic material is reduced, which results in good fluidity, can increase the filling of alloy particles even when low pressure or no pressure is applied, and stress is applied inside the particles. The decrease in permeability can be eliminated. Thus, by combining the metal magnetic particles and the resin, a coil component having high resistance and high characteristics can be obtained. According to a preferred embodiment, the composite magnetic material can be stably filled without increasing the amount of resin by using alloy particles having an oxygen ratio of 30 to 40%, and the thickness of the magnetic material is 0.2 mm, for example. Even if it is thin, a high filling rate can be maintained. In particular, it is possible to make small parts with a lower product height than ever.

The coil component of the present invention is made of a composite magnetic material containing a resin and alloy particles.
An alloy particle is a material configured to exhibit magnetism in a metal portion that is not oxidized, for example, an alloy particle that is not oxidized, or a particle in which an oxide or the like is provided around the particle. Is mentioned. Specifically, a known method for producing alloy particles may be employed, and for example, commercially available as Epson Atmix Co., Ltd. PF-20F, Nippon Atomizing Co., Ltd. SFR-FeSiCr, etc. You can also use what you have. However, many of the alloy particles so far contain about 50 to 90 wt% of iron (Fe element) and 10 wt% or more of elements other than iron (Fe element). This is because the ratio of elements such as chromium (Cr) and silicon (Si) is often increased because the insulation is increased or the core loss is improved. For this reason, it is considered to use the property that the alloy particle surface is easily oxidized with the conventional composition, or to increase the insulation of the particle surface by a method of oxidizing the alloy particle surface by heat treatment, etc. It had been. For this reason, these alloy particles have a high oxygen ratio on the surface of the alloy particles, increase the viscosity resistance as a composite magnetic material, and are not suitable for applications where no pressure is applied.

  For this reason, it is preferable that the content of the Fe element is high as the composition of the alloy particles. The amorphous alloy particles have a content of Fe element of 77 wt%, and the crystalline alloy particles have a content of Fe element of 92.5 wt% or more. Elements such as Mn, P, S, and Mo are used as impurities. May be included. In addition, the Fe element content of the amorphous alloy particles is 79.5 wt% or less, and the Fe element content of the crystalline alloy particles is 95.5 wt% or less, which makes it easy to ensure insulation. . In addition to the Fe element, a substance that is more easily oxidized than Fe, such as Al and Cr, may be included. As elements other than the Fe element, the total of any of Si, Al, Cr, Ni, Mo, and Co is preferably 5 to 10 wt%. Thereby, excessive oxidation of the alloy particle surface can be suppressed, and a stable oxygen ratio can be obtained. For example, in a powder made by a gas atomization method or a powder made by a water atomization method, the oxygen ratio can be adjusted by heat treatment in a reducing atmosphere. At this time, if there is too little oxygen on the surface of the alloy particles, the resistance will decrease, and in order to secure a resistance value, it will be necessary to increase the proportion of things other than metal magnetic particles such as increasing the amount of resin, as a result The filling rate will be lowered. Therefore, the oxygen ratio is preferably adjusted to be 30% or more in terms of ion ratio. The alloy particles include, for example, FeSiCr, FeSiAl, FeNi in a crystalline alloy system, and FeSiCrBC, FeSiBC in an amorphous alloy system.

  Moreover, the material which mixed these 2 or more alloy particles, the material which mixed Fe particle | grains, etc. are mentioned, These particles can combine the particle diameter and a composition, and can obtain the required characteristic suitably. Used. More preferably, the shape of the metal magnetic particles is more preferably spherical. As the particle surface area is smaller, the amount of oxygen on the particle surface can be reduced, the range in which oxygen is present from the particle surface can be minimized, and the proportion of the metal portion in the particle can be increased. The same applies to the surface roughness of the particle surface, and it is desirable that the particle surface be smooth, and the surface roughness Ra is preferably 1 nm to 100 nm.

  The oxygen ratio of the alloy particles is measured by secondary ion mass spectrometry (TOF-SIMS: Time of Flight Secondary Ion Mass Spectrometry, TRIFT-II manufactured by ULVAC-PHI). In TOF-SIMS, secondary ions generated by irradiating a sample (alloy particle) surface layer with a pulsed primary ion beam and stirring the sample surface layer due to collision of the ions and the surface of the sample at the molecular / atomic level are generated. By detecting with a time-of-flight mass spectrometer (TRIFT-II manufactured by ULVAC-PHI), qualitative and quantitative determination of solid components is performed. The quantified oxygen ion concentration corresponds to the ratio of oxygen to the total amount of secondary ions detected.

  In the present invention, the oxygen ratio on the alloy particle surface is 50% or less. More preferably, it is 30 to 40%. The oxygen ratio on the surface of the alloy particles is a numerical value obtained by capturing the change in the oxygen ratio existing at each depth from the surface of the alloy particle toward the inside. Detection is performed by irradiating a primary ion beam of gallium with an acceleration voltage of 15 kV, an ion beam pulse current of 600 pA with a pulse width of 13 nsec, an irradiation time of 60 sec, and an irradiation angle of 40 degrees (angle with respect to the secondary ion detector). The number of ions of each component existing on the sample surface layer is detected from the secondary ions, and the oxygen ratio is obtained here based on the number of ions of each component. In order to obtain the ratio of oxygen existing from the surface of the sample toward the inside, it is necessary to etch the surface of the sample. This etching is performed by continuously irradiating sputtered gallium ions at an acceleration voltage of 15 kV and an ion beam current of 600 pA. Done. Detection and etching are alternately performed for 60 seconds, and detection is performed every 0 minutes (before etching with irradiation with sputter ions) to 1/30 minute etching time, that is, from the surface of the alloy. It is possible to detect a specific component. Moreover, each ion irradiation range was performed in the range of 1-5 micrometers. The measurement was performed so that the metal magnetic particles to be measured fall within this range. In addition, this measurement can be performed at the stage of the metal magnetic particles. For example, when the measurement is performed with a magnetic material containing an organic component, the component other than the component derived from the metal magnetic particle such as the organic component is 20% by weight. It was decided not to exceed. Thereby, even if it is a magnetic body, it can measure as a metal magnetic particle surface by observation of a fracture surface.

  The oxygen ratio of each secondary ion detected becomes the maximum within 10 minutes, preferably between 1 minute and 5 minutes, during the cumulative etching time when the sputter ions are irradiated. Here, the etching time within 10 minutes was defined as the alloy particle surface. In the alloy particles of the present invention, since the maximum value of the oxygen ratio is obtained within a range of 10 minutes or less of the etching time, the oxygen ratio can be correctly evaluated by using the particle surface.

  In conclusion, the “oxygen ratio on the surface of the alloy particles” refers to the maximum value of the ratio from the start of etching to 10 minutes when the oxygen ratio is obtained every minute before and after etching as described above.

  That is, the oxygen ratio of the alloy particle surface is designed. Thereby, the particle surface has good wettability of the resin, and the viscosity resistance of the composite magnetic material is reduced. This is because by reducing the amount of oxygen on the surface of the alloy particles, the hydroxyl groups on the surface of the alloy particles can be reduced and the film of water molecules can be reduced, so the compatibility between the hydrophobic resin and the metal interface is increased, and the surface of the alloy particles and the resin are wetted. Sexuality improves. The viscosity resistance of this composite magnetic material is reduced, which results in good fluidity, can increase the filling of alloy particles even when low pressure or no pressure is applied, and stress is applied inside the particles. The decrease in permeability can be eliminated. This enhances fluidity and can achieve high filling with low pressure. Further, the oxygen ratio on the surface of the alloy particles has a peak point of the oxygen ratio in a range of 10 minutes from the surface layer of the alloy particle, and there are also peak points of elements other than the Fe element. Elements other than the Fe element are determined by the composition of the alloy particles, and include Si, Al, Cr, Ni, Mo, and Co. This is because the insulating properties are ensured by the presence of oxygen other than oxygen and Fe elements on the surface of the alloy particles, and excessive oxidation is suppressed. Thereby, when combined with resin, high resistance and high magnetic properties can be obtained. The oxygen ratio is 50% or less, preferably 30 to 40%. By setting the oxygen ratio to 50% or less in this way, the oxygen ratio of the particle surface layer (before etching) can be set to 25% or less, and the oxygen ratio on the particle surface can be kept low. Furthermore, if the oxygen ratio is 40% or less, the oxygen ratio of the particle surface layer (before etching) can be 20% or less. Preferably, the average value of the time from the start of detection at which the oxygen ratio in the 20 or more metal magnetic particles is maximum is within 10 minutes. Preferably, the average value of the oxygen ratio in 20 or more metal magnetic particles is 50% or less. Regarding the conditions of TOF-SIMS here, when the metal magnetic particles containing 77 wt% or more of Fe element are irradiated with sputter ions for etching, the speed at which the surface layer of the metal magnetic particle is scraped is different from the metal magnetism having different components other than Fe element. Even particles are all within a range of 5% and are almost constant. Also, for the amount of metal surface scraped, convert the detected secondary ions to volume, and calculate the depth scraped from the metal surface by dividing the converted volume by the primary ion irradiation area. Can do.

  The composite magnetic material of the present invention needs to contain the alloy particles as described above, and preferably the oxygen ratio of the alloy particles of 80 vol% or more in the volume ratio of the total metal magnetic particles contained in the composite magnetic material. 30 to 40%. Thereby, a filling rate can be made high and the inductance as a coil component can be made high.

  The composite magnetic material of the present invention needs to contain the alloy particles as described above. Preferably, the average particle size of the alloy particles contained in the composite magnetic material is 2 to 20 μm. Thereby, even if it is a composite magnetic material with a high filling rate, a core loss can be suppressed.

  Preferably, the composite magnetic material includes first metal magnetic particles and second metal magnetic particles, and the first metal magnetic particles and the second metal magnetic particles have different average particle sizes. In the present invention, at least the first metal magnetic particle is an amorphous alloy. At least one of the alloy particles is an amorphous alloy particle. Thereby, core loss can be suppressed. The other alloy particle is an amorphous alloy particle having an average particle size smaller than that of the one alloy particle. Thereby, a filling rate can be raised more. In particular, the filling rate can be maximized by setting the ratio of the respective average particle diameters to 5 times or more. On the other hand, when Fe particles are used, the ratio of the average particle diameter is set to 5 times or more, so that the filling rate can be increased and the current characteristics can be further improved. Moreover, the 3rd (or subsequent) metal magnetic particle which exhibits Fe content ratio different from any of the 1st and 2nd metal magnetic particles may be contained.

  The type of the resin contained in the composite magnetic material of the present invention is not particularly limited, and a resin used for an electronic component or the like can be used as appropriate, and is preferably a thermosetting resin, such as an epoxy resin, a polyester resin, a polyimide resin, Etc. Since this composite magnetic material does not rely on pressure, a magnetic material is formed by applying heat. In particular, it is only necessary to reduce the viscosity when heat is applied, and any resin having a melting temperature of 50 to 200 ° C. may be used. In the case of a coil using a coated conducting wire, if it is 50 to 150 ° C., the quality influence can be prevented without taking any special treatment on the coated conducting wire. From the above point, as an example, a novolac type epoxy resin can be mentioned. In addition, from the viewpoint of ensuring both insulation and improving electrical characteristics, the composite magnetic material preferably contains 5 to 10 wt% of resin. In addition, the flow of the composite magnetic material is improved by making the resin more than 10 wt%. However, the filling rate of the metal magnetic particles decreases conversely and is preferably less than 10 wt%.

  In the present specification, the above-described composition containing the metal magnetic particles and the resin is referred to as a composite magnetic material as a concept of any form. For example, the resin of the composite magnetic material may be cured or uncured. When the resin in the composite magnetic material is cured, and thus the entire composite magnetic material also forms a certain solid shape, the composite magnetic material in such a state is called a “magnetic body”. A magnetic material is also an embodiment of the present invention.

  In the present invention, no pressure is required in obtaining the magnetic material, in other words, in curing. For example, the above-described metal magnetic particles and uncured thermosetting resin are injected into a mold, and the resin is cured by applying it to a temperature higher than the curing temperature of the resin. Moreover, the magnetic body of this invention can be obtained by hardening to a fixed shape. As a result, the metal magnetic particles are not distorted, and the characteristic deterioration can be suppressed. For a method for obtaining a magnetic material from a composite magnetic material, conventional curing techniques for resins can be referred to as appropriate.

  The magnetic body of the present invention is useful as a part of a coil component. The coil component of the present invention can be obtained by forming a coil portion with an insulation coated conductor or the like on the outside or inside of the magnetic body of the present invention. There is no particular limitation on the detailed configuration and manufacturing method of the coil component, and the prior art can be referred to as appropriate.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the embodiments described in these examples.

<Example 1>
Coil parts were manufactured in the following manner.
Product size: 2.5 × 2.0 × 1.2mm
Minimum thickness of magnetic material: 0.25mm
Metallic magnetic particles: FeSiCr (Fe is 92.5 wt%, Si is 4 wt%, Cr is 3.5 wt%, and a powder having an average particle diameter of 15 μm is prepared by a water atomization method in the atmosphere, and the atmosphere is reduced to 500 ° C. The metal magnetic particles were designated as crystalline alloy particles c.)
Resin: Epoxy resin 3wt%
Air-core coil: Rectangular wire with polyimide coating (0.3 x 0.1 mm), α winding and 9.5 t
Molding: An air-core coil is placed inside the mold, and a composite magnetic material is injected into the mold at 150 ° C. by molding and temporarily cured to form a magnetic body.
Curing: Temporarily cured magnetic body is taken out from the mold and cured at 200 ° C. Terminal electrode: The end of the air-core coil is exposed from the magnetic body by polishing, Ag is sputtered, and a conductive paste containing Ag is applied. , Sn plating treatment

The above procedure was performed as follows.
A coil is produced and arranged so that the center of the mold coincides with the center of the air-core coil. Here, the composite magnetic material in which the metal magnetic particles and the resin are mixed in advance is heated to 150 ° C., and the composite magnetic material is injected into a mold heated to 150 ° C., thereby obtaining the source of the magnetic substance. Thereafter, the resin is further cured at 200 ° C. to obtain a magnetic body. Necessary treatments (cutting, polishing, rust prevention treatment) are performed on the magnetic body, and finally a terminal electrode is formed to obtain a coil component. Moreover, the pressure at the time of shaping | molding here was 15 MPa, and was very low with respect to the conventional pressure.

<Comparative Example 1>
A coil component was obtained in the same manner as in Example 1 except that FeSiCr not subjected to the heat treatment in the reducing atmosphere was used as the metal magnetic particle. The metal magnetic particles were designated as crystalline alloy particles a.

<Comparative Example 2>
A coil component was obtained in the same manner as in Example 1 except for the metal magnetic particles. The metal magnetic particles are FeSiAlCr, Fe is 90 wt%, Si is 5 wt%, Al is 4 wt%, Cr is 1 wt%, and a powder having an average particle diameter of 15 μm is prepared by a water atomization method in the atmosphere. Heat treatment was performed for 1 hour in a reducing atmosphere. The metal magnetic particles were designated as crystalline alloy particles b.

<Comparative Example 3>
A coil component was obtained in the same manner as in Example 1 except for the metal magnetic particles. The metal magnetic particles are FeSiCrBC, Fe is 70 wt%, Si is 8 wt%, Cr is 5 wt%, B is 15 wt%, and C is 2 wt%. did. The metal magnetic particles were used as amorphous alloy particles d.

<Example 2>
A coil component was obtained in the same manner as in Example 1 except for the metal magnetic particles. The metal magnetic particles are FeSiCrBC, Fe of 77 wt%, Si of 6 wt%, Cr of 4 wt%, B of 13 wt%, and C of 2 wt%, and a powder having an average particle size of 15 μm is prepared by a water atomization method in the atmosphere. did. The metal magnetic particles were designated as amorphous alloy particles e.

<Example 3>
A coil component was obtained in the same manner as in Example 1 except for the metal magnetic particles. The metal magnetic particles were FeSiBC, Fe was 79.5 wt%, Si was 5 wt%, B was 13.5 wt%, and C was 2 wt%. A powder having an average particle diameter of 15 μm was produced by a water atomization method in the atmosphere. . The metal magnetic particles were designated as amorphous alloy particles f.

<Example 4>
A coil component was obtained in the same manner as in Example 1 except for the metal magnetic particles. As the metal magnetic particles, the amorphous alloy particles f used in Example 3 and the amorphous alloy particles e used in Example 2 having an average particle size of 10 μm different from the particle size are used, and the ratio is 6: 4. It mixed so that it might become, and it was set as the composite magnetic material.

<Example 5>
Here, the product height was changed to 1.0 mm and the minimum thickness of the magnetic material was changed to 0.2 mm, and a coil component was obtained using the same composite magnetic material as in Example 4.

<Example 6>
A coil component was obtained in the same manner as in Example 5 except for the metal magnetic particles. As the metal magnetic particles, amorphous alloy particles f used in Example 3 and amorphous alloy particles e used in Example 2 having an average particle size of 10 μm, which is different from the particle size, are used in a ratio of 8: 2. It mixed so that it might become, and it was set as the composite magnetic material.

<Example 7>
A coil component was obtained in the same manner as in Example 5 except for the metal magnetic particles. As the metal magnetic particles, the amorphous alloy particles f used in Example 3 and the amorphous alloy particles e used in Example 2 having an average particle size of 10 μm different from the particle size are used, and each has a volume of 9: 1. The mixture was mixed to obtain a composite magnetic material.

<Example 8>
A coil component was obtained in the same manner as in Example 5 except for the metal magnetic particles. As the metal magnetic particles, amorphous alloy particles f used in Example 3 and average particle diameters 2 μm different from those of amorphous alloy particles e used in Example 2 were used, and each had a volume of 8: 2. The mixture was mixed to obtain a composite magnetic material.

<Example 9>
A coil component was obtained in the same manner as in Example 5 except for the metal magnetic particles. As the metal magnetic particles, the amorphous alloy particles f used in Example 3 and the average particle size 1.5 μm different from the amorphous alloy particles e used in Example 2 were used. The composite magnetic material was obtained by mixing so that the volume ratio was.

<Example 10>
A coil component was obtained in the same manner as in Example 5 except for the metal magnetic particles. As the metal magnetic particles, the amorphous alloy particles f used in Example 3 and the average particle size of Fe particles (Fe is 99.6 wt%, impurities other than Fe) are 1.5 μm, and each of them is 8: 2. The composite magnetic material was obtained by mixing so as to have a volume ratio.

The SIMS measurement results of the metal magnetic particles contained in the composite magnetic material are as follows.

Metal oxygen particles Oxygen ratio on the surface Crystalline alloy particles a 53%
Crystalline alloy particle b 52%
Crystalline alloy particle c 48%
Amorphous alloy particles d 51%
Amorphous alloy particles e 40%
Amorphous alloy particles f 30%
Fe particles 31%

In the above, “surface oxygen ratio” is the maximum value of the oxygen ratio in the SIMS measurement described above (however, the maximum value in the measurement every minute from 0 to 10 minutes of etching time).
The SIMS measurement was performed on 20 particles for each composite magnetic material. The above is the average of those results.

The resin amount of the composite magnetic material and the inductance of the coil component are as follows.

Filling factor Inductance Example 1 74.0 vol% 1.02 μH
Comparative Example 1 70.3 vol% 0.8 μH
Comparative Example 2 71.2 vol% 0.85 μH
Comparative Example 3 71.3 vol% 0.86 μH
Example 2 75.2 vol% 1.1 μH
Example 3 75.4 vol% 1.12 μH
Example 4 75.8 vol% 1.15 μH
Example 5 75.5 vol% 1.04 μH
Example 6 76.4 vol% 1.1 μH
Example 7 76.1 vol% 1.07 μH
Example 8 77.3 vol% 1.1 μH
Example 9 75.5 vol% 1.02 μH
Example 10 75.5 vol% 1.02 μH

  In the above, the “resin amount” is the amount of resin added during the production of the composite magnetic material, and the “filling rate” is the ratio of the metal magnetic particles in the cross section of the magnetic material determined from a microscopic observation image. “Inductance” indicates an inductance value of the coil component at 1 MHz obtained using an LCR meter.

  In all the comparative examples, the filling rate is low, and a defect (exposed conductor) due to insufficient filling exists around the coil. As a result, the electrical characteristics were lower than those of the examples, and both were sufficient as coil components. As shown in this result, it has been impossible to form a thin portion of the magnetic material until now. On the other hand, in an Example, the magnetic body of thickness 0.25mm and also 0.2mm can be obtained, without producing the defect accompanying filling. As a result, it is possible to cope with the thinning that cannot be achieved with the compacted powder formed at a high pressure, and it is possible to reduce the size of the component.

<Example 11>
In this embodiment, the drum core is wound and a composite magnetic material is formed outside the winding.
Product size: 2.5 × 2.0 × 1.2mm
Drum core: FeSiCr (Fe was 90 wt%, Si was 6 wt%, Cr was 4 wt%, and heat treatment was performed for 1 hour in the atmosphere.)
Composite magnetic material: The above amorphous alloy particles e were used.
Coil: Conductive wire with polyimide coating (flat wire 0.3 x 0.1 mm), 9.5 turns with α winding
Molding: A drum core wound around a rubber mold is placed, and a composite magnetic material is injected into the rubber mold and temporarily cured to form a magnetic body.
Curing: Temporarily hardened magnetic material is taken out from the mold and cured at 200 ° C. Terminal electrode: Ti and Ag are sputtered on the outer surface of the drum core ridge, Ag-containing conductive paste is applied, and Ni and Sn are plated

The above procedure was performed as follows.
The drum core is formed by forming a magnetic material of FeSiCr and performing heat treatment. Next, a terminal electrode is formed on the outer surface of the drum core collar, and a conducting wire wound outside the drum core shaft is connected to the terminal electrode. Finally, the wound drum core is placed in a rubber mold, and the composite magnetic material, in which metal magnetic particles and resin are mixed in advance on the outside of the coil, is heated to 50 ° C to form the composite magnetic material on the outside of the coil. Further, the coil component obtained from the rubber mold is taken out, and the resin is further cured at 200 ° C. to obtain the coil component. Moreover, the pressure at the time of shaping | molding here was 5 Mpa, and was a very low thing with respect to the conventional pressure.

As described above, the coil component was evaluated. As a result, an inductance of 1.15 μH and a filling rate of 74.5 vol% were measured, and current characteristics were good. In addition, stable parts can be made without causing defects such as those associated with filling.
As described above, by using the composite magnetic material of the present invention, it is possible to make the magnetic material thinner and to manufacture a small and high-performance component than ever before.

Moreover, evaluations other than electrical characteristics are shown below.
Each composite magnetic material can be evaluated from the cross section. The filling rate of the metal magnetic particles is obtained by using a scanning electron microscope (SEM) to obtain an SEM image (3000 times) and performing image processing. The ratio of the area of the metal magnetic particles is defined as the filling rate from the area of the metal magnetic particles present in the cross section obtained in this way and the area other than the metal magnetic particles. Separation of the metal magnetic particles in the cross section can be performed by the presence or absence of oxygen, and the particle size (maximum length) that can be seen in the cross section is 1 μm or more as metal magnetic particles. This is in this range because the particle size of the metal magnetic particles smaller than 1 μm has little influence on the magnetic properties.

  The content ratio of iron (Fe element) in the metal magnetic particles can also be measured by SEM-EDX. An SEM image (3,000 times) of a cross section of the composite magnetic material is obtained, particles having the same composition are selected by mapping, and an average value is obtained from the content ratio of iron (Fe element) in 20 or more metal magnetic particles. Moreover, if there exists a thing with a different composition by mapping, it can be judged that the metal magnetic particle of a different composition was mixed. Furthermore, as for the particle size of the metal magnetic particles, an SEM image (about 3000 times) of the cross section of the composite magnetic material is obtained, and 300 or more particles having an average size in the measurement part are selected, and the area in the SEM image is determined. Measure and calculate the particle size assuming that the particles are spheres. Further, from the obtained particle size distribution, if there are two peak points, it can be determined that metal magnetic particles having different average particle sizes are mixed. Each measurement is performed by selecting the central portion of the cross section of the magnetic body formed of the composite magnetic material. In both cases, the size of particles visible in the cross section is 1 μm or more.

Claims (4)

A coil component composed of a composite magnetic material containing alloy particles and a resin, and a coil,
The coil part whose oxygen ratio of the surface of the said alloy particle is 50% or less.   The coil component according to claim 1, wherein the oxygen ratio is 30 to 40%.   The coil component according to claim 1, wherein the coil component has a coil embedded in a composite magnetic material.   The coil component according to claim 1, wherein the coil component has a coil formed inside the composite magnetic material.